A rasp is generally considered to be a special type of file. A rasp is typically used to smooth or shape a relatively soft substrate, such as wood or an animal's hoof. A rasp removes a relatively small amount of material. more than a typical file, but less than a saw, knife, or hoof nippers. Shaping and smoothing an animal's hoof presents some difficult challenges. In trimming an animal's hoof material is usually cut off with another tool. Then the hoof must be smoothed out and, if a shoe is to be attached, must also be leveled or flattened. The surface to be smoothed and shaped is fairly rough and includes at least one generally curved surface. A solid rasp has the problem of filling up with removed material preventing it from removing a sufficient amount of material efficiently. In the past some rasps have been designed with blade-like structures that are either too flexible or too closely spaced to allow material to pass therebetween. More traditional rasps use another type of cutting edge. A flat surface has small portions pushed up leaving a divot in the flat surface and a rounded or triangular mound having a flat side that presents a cutting edge when moved in one direction. The present invention overcomes these problems as set forth below.
An early example of a multi-bladed rasp is U.S. Pat. No. 324,389 issued to Judge and Clayton. This rasp teaches the use of a plurality of parallel blades spaced evenly apart and held in position by a threaded fastener. This rasp is unique in that the blades can pivot about one of their ends. Another early example is U.S. Pat. No. 410,809 issued to Snowden. The Snowden plane has a plurality of parallel blades held by novel means in a block. Both of these planes have problems in that while the blades are relatively rigid they are parallel and do not work properly when passed over a curving or angled surface. They tend to want to travel in a straight line and can unevenly gouge a substrate instead of smoothing it out. Since the blades are straight, they also tend to fill up with removed material and become inefficient.